De-icing device for airplane propellers, wings, and the like



April 1943- J. D. ALTEMUS 2,317,019

DEICING DEVICE FOR AIRPLANE PROPELLERS, WINGS, AND THE LIKE Filed Jan.27, 1941 w l VENTQR1 MATTORNEY.

Patented Apr. 20, 1943 DE-ICIN DEVICE FOR AIRPLANE PRO- PELLERS, WINGS,AND THE LIKE James Dobson Altemus, Roslyn, N. Y.

Application January 27, 1941, Serial No. 376,125

3 Claims.

This invention relates to the prevention of ice formation on thepropeller wings and other vital parts of airplanes, more especially theleading edges thereof and depends for its efficiency upon theutilization of radiant heat for maintaining the edges or areas which itis desired to protect against ice formation at a temperaturesufficiently above the freezing point of water to prevent rain or watervapor from freezing thereon, as well as to effectively melt hail orsleet particles the instant the same impinges or settles upon suchheated edges or areas.

It is well recognized that the range of tcmperatures at which such iceformation occurs on the propellers and wings of airplanes is verylimited and except under extraordinary atmospheric conditions does notexceed about F., but heretofore, due to the intensive cooling effect ofthe rapidly flowing air stream to which said blades and m'ngs aresubjected in flight, the problem of protecting such areas of theairplane against ice formation has failed of successful solution. Sinceradiant heat emanating from a source of infrared rays is howeverremarkably insensitive to defiection or cooling by the air stream whichflows over the propeller blades or wings when the plane is in flight,even at high speeds, and since the temperature range, as above stated,at which ice formation occurs is extremely limited, my improved device,which as above stated utilizes radiant heat rays of the infra-red type,serves to effectively solve this hitherto baiiling problem of iceformation.

My invention is fully described in the following specification anddrawing forming a part thereof, in which latter- Figure 1 is afragmentary plan view of an airplane equipped with my improved deviceand Fig. 2 is an enlarged fragmentary, detailed plan view, partly inhorizontal section, showing the front end of the fuselage and a portionof the propeller.

Referring to the drawing and construction shown therein, the referencenumeral I designates the fuselage of an airplane equipped with theaforesaid device, 2 the wings thereof, 3 the leading edges of the wings,l the hood of the engine compartment, 5 the engine, 6 the propellershaft, 1 the hub thereof, 8 the propeller blades, 9 the propeller noseand ill the hub-cap.

Referring to Fig. 2, it will be observed that the hub-cap is equippedwith oppositely disposed infra-red lamps I5, equipped with reflectors itgenerally of parabolic curvature, concentrating lenses H, at whose focisuch lamps are respectlvely positioned, and cover glasses l8, whichlatter conform to the curvature of the hub-cap. The numeral l9designates the retaining strips which are disposed marginally of theapertures in said nose 9 in which the cover glasses are mounted and thenumeral 20 designates the lead wires which connect the lamps to a sourceof current as a storage battery or generator. The lenses I! serve toproject upon the leading edges of the propeller blades concentratedinfra-red heat rays, as indicated by the reference letter a, which raysare substantially unaffected by the rapid, rearwardly flowing air streamdeveloped by the forward flight of the plane, and these rays serve tomaintain the temperature of such leading edges of the propeller bladessubstantially above the freezing point when conditions are such that icewould otherwise form or collect thereon.

Similar infra-red heating units I5, whose refiectors l6, lenses andcover glasses are of substantially identical construction with theaforesaid units, except for appropriate variation as to size, aremounted in the fuselage and are adapted to likewise protect the leadingedges of the wings by virtue of the concentrated beam essentiallycomposed of infra-red heat rays b projected thereon from such units.

From the foregoing, it will be apparent that the aforesaid device ispeculiarly adapted for effectively preventing ice formation on theleading edges of propeller blades and wings of airplanes. Moreover, ifmetal propeller blades are employed then, if the heat generated by thelamps I5 is of sufiicient intensity to prevent the formation of ice onthe leading edges thereof, the heat conductivity of the metal of theblades will be such that the entire blades will also be protected fromformation of ice thereon.

From actual tests made under conditions simulating that of an airplanein flight, it has been demonstrated by applicant herein that with arelatively small consumption of current it is possible by utilizinginfra-red rays or so-called radiant heat which is essentiallyundefiected by the rapidly moving air currents developed by the flightof the plane, to maintain the leading edges of propeller blades and ofthe wings substantially above the freezing point (32 F.) even though theplane is travelling at high speeds and high altitudes whereas on theother hand, due to the ready deflection of heated air currents, it isimpossible to obtain any appreciable de-icing action on propeller bladesof wings'lf it be attempted to utilize hot air projected by a blower forexample upon the leading edges of the plane or propeller measured incentimeters.

in lieu of a projecting undefiectible radiant rays thereon such asherein described.

As is well known, radiant heat emanating from hot solids and gasesconstitutes essentially electromagnetic waves of substantially invisibleinfrared rays whose wave lengths range between those of the rays of thered end of the visible spectrum, the various visible rays whereof areusually measured in microns or even millimicrons, on the one hand, andthe wave lengths of the so-called wireless or hertzian waves whichlatter are usually These infra-red rays can be reflected or refractedthe same as the visible rays of the spectrum. Ordinary glass, however,is substantially opaque to the passage of these infra-red rays. However,modern glass makers have developed glasses of special composition whichhave a relatively low absorption index for these rays. Also substancessuch as sylvin and fluorite effectively transmit these infra-red rays.Moreover, quartz, in thicknesses of a centimeter or at most a fewcentimeters, effectively transmits these infra-red rays, especiallythose whose wave length exceeds 70 microns, although quartz, is highlyabsorptive of infra-red rays of a wave length approaching that of therays of the visible spectrum.

In view of the aforesaid characteristics of these infra-red rays, theconcentrator lenses H and cover glasses I8 are composed desirably ofsylvin, fluorite, thin sections of quartz, or special glass capable ofeflectively transmitting infra-red rays instead of ordinary glass suchas employed for cheap reflectors of visible light rays.

Various modifications within the scope of the heat appended claims maybe made without departing from the spirit of my invention.

Having thus described my invention, I claim:

1. The combination with the supporting plane and propeller of anairplane, of a source of electromagnetic infra-red radiant heat rayscarried by the airplane and means for directing electromagnetic heatrays, emanating from said source, on the leading edges of at least oneof the propeller and supporting plane members said means including aconcentrating lens disposed in front of said source composed of amaterial which is highly transparent to infra-red rays developed by suchsource.

2. In an airplane, the combination with a supporting plane and apropeller, of a plurality of separated sources of radiant heat energymounted on said airplane and one of said sources being located inimmediate proximity to the hub of said propeller and a reflector elementdisposed at the rear of each of said sources and ray-concentrating meansdisposed in front of each of said sources, said concentrating meansbeing highly transparent to infra-red radiant heat waves developed bysaid sources and arranged to project said radiant heat waves against theleading edges of at least one of the supporting plane and JAMES DOBSONALTEMUS.

